Selective reaction of fatty acids and their separation

ABSTRACT

A PROCESS FOR MAKING A DICARBOXYLIC ACID HAVING 21 CARBON ATOMS FROM FATTY ACIDS IS ACCOMPLISHED BY REACTING THE LINOLEIC ACID PORTION IN A FATTY ACID MIXTURE WITH UP TO 26% BY WEIGHT OF FATTY ACIDS OF ACRYLIC ACID AND WITH FROM 0.01% TO 0.5% BY WEIGHT OF FATTY ACIDS OF IODINE CATALYST AT A TEMPERATURE BETWEEN 200*C. AND 270*C. THE FATTY ACID-DICAROXYLIC ACID MIXTURE IS THEN SEPARATED BY DISTILLING INTO AN OLEIC-TYPE FATTY ACID AND A G21 DICARBOXYLIC ACID. THIS PROCESS IS ESPECIALLY APPLICABLE TO SEPARATING TALL OIL FATTY ACIDS.

United States Patent O 3,753,968 SELECTIVE REACTION OF FATTY ACIDS AND THEIR SEPARATION Benjamin F. Ward, Charleston, S.C., assignor to Westvaco Corporation, New York, N.Y. No Drawing. Filed July 1, 1971, Ser. No. 159,070 Int. Cl. C09F N04 US. Cl. 26097.6 4 Claims ABSTRACT OF THE DISCLOSURE A process for making a dicarboxylic acid having 21 carbon atoms from fatty acids is accomplished by reacting the linoleic acid portion in a fatty acid mixture with up to 26% by weight of fatty acids of acrylic acid and with from 0.01% to 0.5% by weight of fatty acids of iodine catalyst at a temperature between 200 C. and 270 C. The fatty acid-dicarboxylic acid mixture is then separated by distilling into an oleic-type fatty acid and a C dicarboxylic acid. This process is especially applicable to separating tall oil fatty acids.

BACKGROUND OF THE INVENTION This invention relates to the production of a dicarboxylic acid having 21 carbon atoms. It also relates to a process for the separation of fatty acids. More specifically, this invention relates to a process for making dicarboxylic acid having 21 carbon atoms from tall oil derived linoleic acid. As used herein the term dicarboxylic acid is intended to mean a dicarboxylic acid having 21 carbon atoms, but in some instances includes minor amounts of dicarboxylic acid or other molecular weights.

The invention outlined below is to be distinguished from treatment of tall oil fatty acids with iodine as set forth in US. Pat. 3,157,629 to P. D. Patrick. In the Patrick process, tall oil fatty acids are heated Within a range of 450550 F. (232 C.288 C.) in the presence of an iodine catalyst until the linoleic acid portion of the fatty acid is reduced below 15%, forming saturated acids, primarily oleic acid and 2-25% dimerized acids. -In contrast, in the process of this invention, the linoleic acid is not converted to oleic acid. The process of this invention is also to be distinguished from US. Pats. 2,617,- 792 to Floyd, and 2,811,386 to Hasselstrorn. In these processes, the tall oil starting material contains a relatively large proportion of rosin acids and is subjected to heat in the presence of a catalyst, whereupon hydrogen is generated largely from the rosin acids and serves to hydrogenate certain rosin acids as well as the unsaturated fatty acids. The reactions above do not accomplish the results of this invention.

The use of dicarboxylic acids is well known in the prior art as dicarboxylic acids are useful as plasticisers in the manufacture of alkyd resins and as curing agents for epoxy resins. A process for making dicarboxylic acid from fatty-type acids is disclosed in British Pat. No. 1,032,363, wherein conjugated fatty acids are isomerized to a trans/trans form with iodine and subsequently reacted with a reactive dienophile to form the Diels-Alder adduct. However, the disclosed reaction has heretofore not been applied to fatty acids containing non-conjugated linoleic acid wherein the non-conjugated linoleic acid is converted to dicarboxylic acid.

It is therefore a general object of this invention to provide a process for making dicarboxylic acid from all of the available linoleic acid in a fatty acid mixture. Another object of this invention is to provide a process whereby tall oil fatty acids may easily be separated into a dicarboxylic acid portion and an oleic acid-type portion.

Other objects, features and advantages will be evident from the following disclosure.

Patented Aug. 21, 1973 It has been found that if a fatty acid mixture containing a significant portion of linoleic acid is treated with up to 26% by weight of fatty acids of acrylic acid and from 0.01% to 0.50% by weight of fatty acids of iodine at a temperature between 200 C. and 270 C., the linoleic acid portion of the fatty acid mixture is converted to dicarboxylic acid. Thus when the fatty acid mixture is a tall oil fatty acid mixture, and stabilized glacial acrylic acid, and iodine catalyst are heated together at 230 C.- 250 C. for about one to two hours, they produce a dicarboxylic acid along with the residual monounsaturated and saturated fatty acids. Upon distillation, a high grade oleic acid is obtained; the residue being dicarboxylic acid. Such separation of the oleic and linoleic acids in tall oil is not possible by fractional distillation of the fatty acids prior to reaction with acrylic acid.

DETAILED DESCRIPTION OF THE INVENTION There is provided by this invention a convenient process for upgrading crude and distilled fatty acids by forming different acids from one portion of the fatty acid and separating the fatty acids into distinct major fractions. Until this invention, it has been difficult to fractionally distille tall oil fatty acids into component acids because of their close boiling points. The invention is based on conversion of the total diene portion of fatty acids to dicarboxylic acid, which has a significantly higher boiling point than oleic acid.

Accordingly, tall oil fatty acids containing both nonconjugated and conjugated linoleic acid are reacted with acrylic acid in the presence of catalytic amounts of iodine. The acrylic acid is added to the fatty acid mixture in an amount up to about 12% by weight of fatty acids. The catalytic amounts of iodine used is from 0.01% to 0.50% based on the weight of fatty acids, preferably 0.05% 0.2% by weight. The upper amount gives rapid reaction without unnecessary loss of color. If large percentages of iodine are used, i.e., above 0.5%, or if the reaction temperature is increased above 270 C. a portion of the linoleic acid is converted to oleic acid and the yield of dicarboxylic acid is thereby decreased. There is a lower limit of feasibility too, for at just slightly milder reaction conditions the rate drops to almost zero. In order to maintain the highest possible yield of dicarboxylic acid from a mixed fatty acid, conditions close to the lower catalyst level and lower temperature are maintained. Selection of the ideal amount of catalyst will depend on the equipment, temperature and time of the reaction. The reaction to produce dicarboxylic acid is carried out at a temperature between 200 C. and 270 C., preferably 230 C.250 C. The reaction time at these temperatures and under the preferred catalyst level is about one to two hours.

The following is typical of the general procedure which may be used in carrying out the process of this invention on tall oil fatty acids.

To tall oil fatty acids is added up to 12% by weight of fatty acids of glacial acrylic acid and 0.1% by weight of fatty acids of iodine, at a temperature between 230 to 25 0 C. The acrylic acid catalyzed by iodine readily undergoes reaction with the fatty acids. Therefore, when tall oil fatty acids, acrylic acid and iodine are mixed together and heated to 250 C., the linoleic acid in the fatty acids is converted to dicarboxylic acid. In addition to the advantage of having a one step reaction in this case, it seems that the iodine catalyzes the addition reaction to get a very clean, rapid reaction. This one step process greatly improves the overall yield of dicarboxylic acid from fatty acids containing linoleic acid because all of the linoleic acid is immediately converted to dicarboxylic acid. The

amount of dicarboxylic acid formed is approximately the same as the starting content of linoleic in the fatty acid mixture. This process is equally applicable to fatty acids derived from sources other than tall oil, such as animal derived and vegetable derived fatty acid mixtures contain tions A-D in Table I. As can be seen, the reaction occurs at 205 C., but for optimum utility and maximum yield of dicarboxylic acid Within a reasonable time a temperature of about 250 C. is preferred. Reactions E-H show the effect of various catalyst levels and again a variety of ing substantial amounts of linoleic acid. addition levels will promote the reaction but these results One of the major advantages of this process is that tall are shown with 0.075% to 0.15% iodine. oil fatty acids may be separated into two fractions by The time required for maximum conversion of linoleic distillation. In a fractional laboratory distillation a 5% acid to dicarboxylic acid depends on temperature and heads cut is taken and then, one gets 50% of the feed as catalyst level. As is demonstrated in reactions H-J, if the distillate. The remaining 45% is dicarboxylic acid which temperature is 250 C. and 0.15% iodine is used about can be further purified, if desired, by molecular distilla- 45 minutes is required for complete conversion of the tion. Using the fractional distillation method of purificalinoleic acid in the tall 011 to dicarboxylic acid. The gas tion, a distillate which is very similar to oleic acid is obchromatography data. shows that only the linoleic acid is tained. This product is about 75% C monounsaturated reacting (percentage decreasing). There is very little fatty acids, has an acid number of 195, has only 3% diene, change in the fatty acids present in the tall oil except for and has a titer of about C. the reaction of the linoleic acid, thus, one obtains a mix- The crude dicarboxylic acid material, which accounts ture of tall oil fatty acid (virtually linoleic free) and the for 45% of the total, is about 92% dioarboxylic acid. dicarboxylic acid.

TABLE I [Variations in reaction conditions for reaction of distilled tall oil fatty acids with acrylic acid] Untreated Reaction number fatty acid A B C D E F G H I .r

A. Conditions:

Temperature, C 205 219 232 252 250 250 250 250 250 250 P entmdine 0.06 0. 6 7 0. 6 0.075 0.1 0.125 0.15 0,15 115 Time, hrs 2 a 2. 5 2. 5 2 1. 2 1 0. 5 0. 75

B. Analysis by GLC assignment:

Saturated fatty acid 5.1 6.1 0 4.3 4. 6 4. 6 4.6 4.1 5.3 5 6 01s monounsaturated fatty acid 45. 0 45. 7 47.2 46.6 45.0 44. 5 44. 9 44. 4 44. 8 44. 5 45. 0

Linoleic acid 41.4 -8 2 5 6.3 2.4 2.0 1. 4 5,4 0, 6

Other fatty acids 8.6 11.8 10.0 9.8 10.2 10.7 9.1 9.0 10.7 8.3 as

C21 dicarboxylic acid acid 0.0 12.0 20.0 24.0 35.0 34.0 39.0 40.0 40.0 30.0 42.0

The impurities are about 5% fatty acids and 5% dimer- EXAMPLE 2 type fatty ac ds- T1118 mammal 15 Father dark smfie 1t 13 a This example illustrates separation and characterization bottoms product and must be purified to get a high grade of C21 dicarboxylic acid The acid mixture fro th dicarboxylic acid. The C dicarboxylic acid from linoleic action of distilled tau n fan acids iodine acvid with two acid g oups is shown below. The theoretical acid can be Separated into i fractions fr i acid numbe is 316 and that of the Crude dicarboxyhc 4O distillation in a short path still with an inch of las s liez i s a asd isesagfiuf 308 due t0 the lmPuntms hsted above whlch in it to serve as plates. From this drsullatron a 4% heads a P fraction (100% fatty acids); 50% distillate fraction /OH=CH (97.2% fatty acids, 2.8% dicarboxylic acid); and

CH;(CH2)5GH oH-(cHz)7-ci-011 residue fraction (4.7% fatty acids, 92.1% dicarboxylie 45 acid, and 3.2% other) was obtained. The analysis of I each fraction was by gas chromatography. The other" X X portion of the residue fraction represents unidentified mawherein one X is a hydrogen (H) and the other X is a renal which does not come out in the dicarboxylic acid carboxylic acid group (COOH). peak. Most of this other material is a dimer fatty acid.

Another means, other than molecular distillation, for For the sample reported above the residue had an acid purifying the crude dicarboxylic acid is by distillation of number of 300, a saponification number of 304, a Gardner its methyl or dimethyl ester. At 0.2 mm. vacuum the (11- color of 16, and a Gardner viscosity of more than Z-6. carboxylic acid boils at 265 C., the monomethyl ester The residual dicarboxylic acid fraction was distilled at boils at 240 C., and the dimethyl ester boils at 220 C. 270 C. at 0.2 mm. to obtain a somewhat purer dicar- Therefore, by converting the crude dicarboxylic acid to its boxylic acid. However, at these high temperatures (300 dimethyl ester and then distilling, a very pure product C. pot temperature) decomposition of the dicarboxylic can be obtained. The separation from dimer acid is very acid began to occur. One of the ways for purifying the good too, since the dimethyl ester of any dimer and dicarboxylic acid is to convert it to its dimethyl ester present boils at least above about 260 The dimethyl and then distill this. The competitive distillation temester and the monomethyl ester of the dicarboxylic acid peratures of various esters are reported in Table 11.

are readily purified by fractlonal distillation; whereas the TABLE H fi fhcarboxyhc acid 15 best separated by molecular dis- [Distillation temperatures for materials in the dlcarboxylic acid 11111311011. system] The practice of this invention may clearly be seen in P 0t Vapor the following examples. ppu m 0.) C (inm.) EXAMPLE 1 Fatty acid monomer. 200 190 D. 2

To illustrate the production of C dlCfifbOXYll? acid, gggg g ggfig- '33? 54% 3:3 a series of reaction involving the addition of acrylic acid Monornethylester oidicarboxyllc acid- 205 240 0.2 to tall oil fatty acids were run. The reaction conditions g$ggffff 558 8:; and results are shown in Table I.

In these reactions 12% by Weight f the fa ty a ds Of As is illustrated by the results in Table II, by preparing glacial acrylic acid was added to the linoleic acid portion the dimethyl ester of dicarboxylic acid and purifying it of distilled tall oil fatty acids in the presence of an iodine by distillation, the fatty acid monomer and the dimer acids catalyst. The effect of temperature is illustrated by reaccan be cleanly removed. In a sample treated in this manner and then reacidified, the gas chromatograph showed the sample to be 93% dicarboxylic acid. It has an acid number of 310.

While the invention has been described and illustrated herein by references to various specific materials, procedures and examples, it is understood that the invention is not restricted to the particular materials, combinations of materials, and procedures selected for that purpose. Numerous variations of such details can be employed, as will be appreciated by those skilled in the art.

What is claimed is:

1. A process for the production of a dicarboxylic acid from a fatty acid mixture containing conjugated linoleic acid non-conjugated linoleic acid comprising, simultaneously reacting both the non-conjugated and conjugated linoleic acid portion of the fatty acid mixture with up to 26% by weight of said fatty acids of acrylic acid and 0.01% to 0.50% by Weight of fatty acid mixture of iodine at a temperature between 200 C. and 270 C. to convert the conjugated and non-conjugated linoleic acid portion to a dicarboxylic acid having the formula wherein one X is hydrogen and the other X is a carboxylic acid group.

2. The process of claim 1 wherein said fatty acid mixture is a tall oil fatty acid mixture.

3. The process of claim 1 wherein said iodine is present at 0.05 to 0.20% by weight and said temperature is between 230 C. and 250 C.

4. The process of claim 1 further comprising, distilling the fatty acid mixture containing dicarboxylic acid and recovering a linoleic free fatty acid fraction and a dicarboxylic acid fraction.

References Cited FOREIGN PATENTS 1,032,363 6/1966 Great Britain 26097.5

VIVIAN GARNER, Primary Examiner US. Cl. X.R.

2 2 3 UNETED STATES PATENT OFFICE QERTEFECATE 6F CORRECTIQN Patent No. 3,7 3, 8 Dated August 21 1973 l Benjamin F. ward It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Co1umn I line 33, ""or" should read of Co1um'n 3, Hne 69, "reaction" should read react1'ons a i.-

Claim 1, line 3, "acid", first occurrence, should read and CH=CH 0 -u Glam 1, the formula should read- CH CH -CH CH-(CH -C-0H CH-CH i I l X Signed and sealed this 26th day of March 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents 

